Tire wheel assembly

ABSTRACT

Disclosed is a tire wheel assembly allowed to enhance working efficiency in rim assembling without destabilizing mounting of a run-flat support member, and furthermore, allowed to realize noise reduction by improving a vibration characteristic during normal traveling. The tire wheel assembly is one where, while a pneumatic tire is fitted to a rim of a wheel, inserted into a cavity portion of the pneumatic tire is a run-flat support member formed of a pair of elastic rings fitted to the rim; and an annular shell straddling between the elastic rings. In the tire wheel assembly, inner diameters of the pair of elastic rings are made different from each other to make an inner diameter of one elastic ring fitted to the rim in a back side of the wheel smaller than an inner diameter of the other elastic ring fitted to the rim in a front side of the wheel.

TECHNICAL FIELD

The present invention relates to a tire wheel assembly realizingrun-flat traveling, and more specifically, relates to a tire wheelassembly allowed to enhance working efficiency in rim assembling withoutdestabilizing mounting of a run-flat support member.

BACKGROUND ART

Even when a pneumatic tire goes flat, a number of technologies, whichenables the tire to make an emergency run for a reasonable amount ofmileage, have been proposed in response to the market demanding such atechnology as above. Among the thus proposed technologies, there is atechnology which realizes run-flat traveling in a manner that, with acore being mounted on a rim inside a cavity portion of a pneumatic tire,the pneumatic tire in a deflated condition is supported by the core (forexample, refer to Patent Documents 1 to 3).

A run-flat support member as described above is formed of aconfiguration: which includes an annular shell formed in a structurewith legs astride which, while having an abutting portion projected onan outer peripheral side of the structure, has legs along both sides ofthe abutting portion, the abutting portion being intended to abut aninner surface of a tire; and where elastic rings are respectively fixedto these legs. The run-flat support member is intended to be mounted onthe rim through the elastic rings. According to this run-flat supportmember, the run-flat support member can be used, substantially withoutadding any particular modifications to existing wheel and rim, with theexisting wheel and rim as they are, and hence have an advantage that itcan be made acceptable to the market without bringing any seriousconfusion to the market.

When the above run-flat support member is mounted onto a tire wheelassembly, it is necessary to insert the run-flat support member in acavity portion of a pneumatic tire at first, and then to perform rimassembling work of the pneumatic tire in a state where this run-flatsupport member is contained therein. For this reason, for the purpose offacilitating the rim assembling work, it is desired that the elasticrings of the run-flat support member easily go over rim flanges, thatis, inner diameters of the elastic rings be as large as possible.However, if the inner diameters of the elastic rings are made uniformlylarge, there arises a problem that the mounting of the run-flat supportmember becomes unstable.

[Patent Document 1] Japanese patent application Kohvo publication No.2001-519279

[Patent Document 2] Japanese patent application Kokai publication No.2001-163020

[Patent Document 3] Japanese patent application Kokai publication No.Hei10-297226

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a tire wheel assemblyallowed to enhance working efficiency in rim assembling withoutdestabilizing mounting of a run-flat support member, and furthermore,allowed to realize noise reduction by improving a vibrationcharacteristic during normal traveling.

A tire wheel assembly of the present invention for achieving the aboveobject is one where, while a pneumatic tire is fitted to a rim of awheel, a run-flat support member is inserted into a cavity portion ofthe pneumatic tire, the run-flat support member being formed of a pairof elastic rings fitted to the rim; and an annular shell straddlingbetween the elastic rings. The tire wheel assembly is characterized inthat inner diameters of the pair of elastic rings are made differentfrom each other to make an inner diameter of one elastic ring fitted tothe rim in a back side of the wheel smaller than that of the otherelastic ring fitted to the rim in a front side of the wheel.

In the present invention, an outer diameter of the run-flat supportmember is formed to be smaller than an inner diameter of a tread portionof the pneumatic tire for the purpose of keeping the run-flat supportmember and the pneumatic tire apart in a constant distance. On the otherhand, an inner diameter thereof is formed to have a measurementsubstantially equal to an inner diameter of a bead portion of thepneumatic tire. This run-flat support member constitutes a tire wheelassembly in a manner that it is mounted onto a rim with a pneumatic tirein a state where it is inserted into a cavity portion of the pneumatictire. When the pneumatic tire goes flat while a vehicle is running withthe tire wheel assembly mounted thereon, run-flat traveling becomespossible because the flat tire in a deflated condition goes into a statewhere it is supported by the run-flat support member.

In the present invention, in consideration of working efficiency in rimassembling and of noise due to road noise, the inner diameters of thepair of elastic rings are made different from each other. That is,because the elastic ring and the tire bead portion both intended to bearranged in the front side of the wheel do not easily go over a rimflange in the front side of the wheel at the time of rim assembling, theinner diameter of the elastic ring in the front side of the wheel ismade relatively large. Thereby, working efficiency in rim assembling canbe improved. On the other hand, because the elastic ring and the tirebead portion both intended to be arranged in the back side of the wheeleasily go over the rim flange in the front side of the wheel, andadditionally because vibration is more likely to occur in the back sideof the wheel, the inner diameter of the elastic ring in the back side ofthe wheel is made relatively small. Thereby, an effect of reducing roadnoise in a frequency band of 400 to 500 Hz is obtained. Moreover,although the inner diameter of the elastic ring in the front side of thewheel is made relatively large, mounting of the run-flat support memberis not destabilized because the inner diameter of the elastic ring inthe back side of the wheel is made relatively small.

In the present invention, for the purpose of compatibly achieving theworking efficiency in rim assembling and the vibration characteristic,it is preferable that the inner diameter of the elastic ring fitted tothe rim in the back side of the wheel be at least 0.2 mm smaller thanthat of the elastic ring fitted to the rim in the front side of thewheel. More specifically, it is preferable: that the inner diameter ofthe elastic ring fitted to the rim in the back side of the wheel be setin a range obtained by adding −1.5 to 0.0 mm to an outer diameter of ahump in the back side of the wheel; and that the inner diameter of theelastic ring fitted to the rim in the front side of the wheel be in arange obtained by adding −0.2 to 0.7 mm to an outer diameter of a humpin the front side of the wheel.

Particularly for the purpose of improving the vibration characteristic,it is preferable that a reinforcement core be buried in the elastic ringfitted to the rim in the back side of the wheel, the reinforcement corebeing continuous in a circumferential direction of the tire wheelassembly. Additionally, it is preferable to provide a projection, whichis continuous in the circumferential direction of the tire wheelassembly, on one side of a radially inner end portion of the elasticring fitted to the rim in the back side of the wheel, the one side beingoutward in an axial direction of the tire wheel assembly. In this case,not only an effect of improving the vibration characteristic can beobtained, but stability of mounting of the run-flat support member canbe enhanced. A height and a width of the above projection may be inranges respectively of 0.4 to 1.5 mm and of 5.0 to 15.0 mm. Furthermore,if a radially inner end portion of the elastic ring fitted to the rim inthe back side of the wheel is recessed in the same shape as the hump,the vibration reduction effect is obtained as obtained in the abovemanner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a main portion of a tire wheelassembly configured of an embodiment of the present invention, takenalong a meridian thereof.

FIG. 2 is a cross-sectional view showing an individual unit of anunattached run-flat support member of the present invention, taken alonga meridian thereof.

FIG. 3 is a cross-sectional view showing an modification example of anelastic ring for the run-flat support member of the present invention.

FIG. 4 is a cross-sectional view showing another modification example ofan elastic ring for the run-flat support member of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, a detailed description will be given of a configuration ofthe present invention with reference to the attached drawings.

FIG. 1 is a cross-sectional view showing a main portion of a tire wheelassembly (tired wheel) configured of an embodiment of the presentinvention, taken along a meridian thereof, and reference numerals 1, 2,and 3 denote a rim of the wheel, a pneumatic tire, and a run-flatsupport member, respectively. These rim 1, pneumatic tire 2 and run-flatsupport member 3 are respectively formed in annular shapes whose centeris commonly an unillustrated rotational axis of the wheel.

The run-flat support member 3 is constituted of an annular shell 4 andelastic rings 5 as main members. The run-flat support member 3 is apartfrom an inner surface of the pneumatic tire 2 during normal traveling,but supports, from within, the pneumatic tire 2 in a deflated conditionwhen it goes flat.

The annular shell 4 is formed in a structure with legs astride where,while an abutting portion 4 a, which abuts an inner surface of the tirein a deflated condition, is projected on an outer peripheral side (on aradially outward side) of the structure, legs 4 b, 4 b are providedalong both sides of the abutting portion 4 a. The abutting portion 4 aof the annular shell 4 is formed in order that a profile of an outersurface thereof can form a convex curved surface on an outer peripheralside in a cross section taken along a direction orthogonal to acircumferential direction thereof. At least one such convex curvedsurface may be provided, but it is preferable that at least two suchconvex curved surfaces be aligned in an axial direction of the tire. Byforming the abutting portion 4 a of the annular shell 4 with the two ormore convex curved surfaces being aligned therein, locations where theabutting portion 4 a contacts the inner surface of the tire aredistributed among two or more locations, whereby local abrasion given tothe inner surface of the tire is reduced. Therefore, a sustainablemileage of run-flat traveling can be extended.

The above annular shell 4 is as thin as 0.5 to 5.0 mm in thickness, andis constituted of a highly stiff material in order to support a weightof a vehicle through the tire in a deflated condition. For theconstituting material thereof, a metal, a resin or the like can be used.For the metal, steel, aluminum and the like can be cited. For the resin,any one of a thermoplastic resin and a thermosetting resin isapplicable. As the thermoplastic resin, nylon, polyester, polyethylene,polypropylene, polystyrene, polyphenylene sulfide, ABS and the like canbe cited, and as the thermosetting resin, an epoxy resin, an unsaturatedpolyester resin and the like can be cited. The resin may be used only byitself, or may be used as a fiber-reinforced resin with reinforcingfibers blended therein.

The elastic rings 5 are respectively fixed to legs 4 b, 4 b of theannular shell 4, and are intended to support the annular shell 4 whileabutting left and right sides of a rim sheet. These elastic rings 5stably support the annular shell 4 by preventing the annular shell 4from slipping against the rim sheet, as well as reducing shock andvibration received by the annular shell 4 from the pneumatic tire 2 in adeflated condition.

As a material constituting the elastic rings 5, rubber or a resin can beused, and in particular, rubber is preferable. As the rubber, naturalrubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR),butadiene rubber (BR), hydrogenated NBR, hydrogenated SBR,ethylene-propylene rubber (EPDM or EPM), butyl rubber (IIR), acrylicrubber (ACM), chloroprene rubber (CR), silicon rubber, fluoro rubber,and the like can be cited. Needless to say, additives such as a filler,a vulcanizer, a vulcanization accelerator, a softener and an antioxidantcan be blended in the rubber appropriately. Here, a desired elasticitycan be obtained based on a blend of the rubber composition.

In the tire wheel assembly thus configured, when the tire goes flatduring traveling, the pneumatic tire 2 in a deflated condition goes intoa state where it is supported by the run-flat support member 3, wherebyrun-flat traveling becomes possible.

In the above tire wheel assembly, a pair of the elastic rings 5, 5 haveinner diameters different with each other, and an inner diameter of theelastic ring 5 fitted to the rim 1 in a back side Wi of the wheel (aninward side with respect to a vehicle) is smaller than an inner diameterof the elastic ring 5 fitted to the rim 1 in a front side Wo of thewheel (an outward side with respect to a vehicle). That is, as shown inFIG. 2, in an individual unit of the run-flat support member 3 before itis attached to the rim 1, the inner diameter Di of the elastic ring 5for the back side Wi of the wheel is smaller than an inner diameter Doof the elastic ring 5 for the front side Wo of the wheel.

During rim assembling, the elastic ring 5 intended to be arranged in thewheel back side Wi is mounted, together with a bead portion of the tire,onto the rim 1 through the wheel front side Wo, and then the elasticring 5 intended to be arranged in the wheel front side Wo is mounted,together with another bead portion of the tire, onto the rim 1 throughthe wheel front side Wo. In this occasion, although it is otherwisedifficult for the elastic ring 5 intended to be arranged on the wheelfront side Wo to go over, together with the tire bead portion, a rimflange in the wheel front side Wo, if the inner diameter Do of theelastic ring 5 in the wheel front side Wo is made relatively large asdescribed above, it becomes possible to improve working efficiency inrim assembling.

On the other hand, it is easy for the elastic ring 5 arranged in thewheel back side Wi to go over, together with the tire bead portion, therim flange in the wheel front side Wo, and additionally, vibration ismore likely to occur in the wheel back side Wi. In this respect, if theinner diameter Di of the elastic ring 5 in the wheel back side Wi ismade relatively small, road noise can be reduced in a frequency band of400 to 500 Hz. Moreover, although the inner diameter Do of the elasticring 5 in the wheel front side Wo is made relatively large, mounting ofthe run-flat support member 3 is not destabilized because the innerdiameter Di of the elastic ring 5 in the wheel back side Wi is maderelatively small.

In the above tire wheel assembly, it is preferable that the innerdiameter Di of the elastic ring 5 in the wheel back side Wi be at least0.2 mm smaller than the inner diameter Do of the elastic ring 5 in thewheel front side Wo. If a difference between the inner diameters Di andDo is less than 2.0 mm, the above operational effects becomeinsufficient.

In FIG. 1, while humps 1 a are provided to the rim 1 in positions nextto the rim sheet, the inner diameters Di and Do may be formed inappropriate measurements relative to outer diameters of the humps 1 a.That is, the inner diameter Di of the elastic ring 5 in the wheel backside Wi may be set in a range obtained by adding −1.5 to 0.0 mm to anouter diameter di of the hump 1 a in the wheel back side Wi, and thatthe inner diameter Do of the elastic ring 5 in the wheel front side Womay be set in a range obtained by adding −0.2 to 0.7 mm to an outerdiameter do of the hump 1 a in the wheel front side Wo. If the innerdiameter Di of the elastic ring 5 in the wheel back side Wi is smallerthan the above range, the working efficiency in rim assembling isdeteriorated, and to the contrary, if it exceeds the above range, areduction effect on road noise becomes insufficient. On the other hand,if the inner diameter Do of the elastic ring 5 in the wheel front sideWo is smaller than the above range, working efficiency in rim assemblingis deteriorated, and to the contrary, if it exceeds the above range,mounting stability of the run-flat support member 3 is deteriorated.

As shown in FIG. 1, a reinforcement core 6 may be buried at least in theelastic ring 5 in the wheel back side Wi, the reinforcement core 6 beingcontinuous in a circumferential direction of the tire wheel assembly.This reinforcement core 6 is constituted of a material, such as a metalor a resin, which is higher in stiffness than the material constitutingthe elastic rings 5. For the metal, steel, aluminum or the like can beused. On the other hand, for the resin, any one of a thermoplastic resinand a thermosetting resin is applicable. As the thermoplastic resin,nylon, polyester, polyethylene, polypropylene, polystyrene,polyphenylene sulfide, ABS and the like can be cited, and as thethermosetting resin, an epoxy resin, an unsaturated polyester resin andthe like can be cited. The resin may be used only by itself, or may beused as a fiber-reinforced resin with reinforcing fibers blendedtherein.

The above reinforcement core 6 may have a configuration obtained bywinding up a reinforcing cord formed of a metal cord such as a steelcord, or of an organic-fiber cord such as a nylon cord. In the case ofthus winding up the reinforcing cord, one such reinforcing cord may bewound up, or a plurality of such reinforcing cords may be wound up in abundle.

In the above tire wheel assembly, at least with respect to the elasticring 5 in the wheel back side Wi, a projection 5 b continuous in thecircumferential direction of the tire wheel assembly may be provided onone side of a radially inner end portion 5 b of the elastic ring 5, theone side being outward in an axial direction of the tire wheel asembly.The projection 5 b as described above enhances mounting stability of therun-flat support member 3, as well as preventing vibration fromoccurring by pressing the rim 1 in an immobilized state. A height of theprojection 5 b in a radial direction of the tire and a width thereof inan axial direction of the tire may be in ranges of 0.4 to 1.5 mm and of5.0 to 15.0 mm, respectively.

Furthermore, in the above tire wheel assembly, at least with respect tothe elastic ring 5 in the wheel back side Wi, as shown in FIG. 4, theradially inner end portion 5 a of the elastic ring 5 may be recessed inthe same shape as the hump 1 a. In this case, because an area of aninterface between the elastic ring 5 and the rim 1 becomes large,vibration of the rim 1 is reduced more effectively.

While the detailed description has been given of the preferredembodiment of the present invention hereinabove, it should be understoodthat various modifications to, substitutions for, and replacements withthe embodiment can be carried out as long as the modifications, thesubstitutions, and the replacements do not depart from the spirit andthe scope of the present invention defined by the attached scope ofclaims.

EXAMPLES

A tire wheel assembly formed of a pneumatic tire, which has a tire sizeof 205/55R16 89V, and a wheel, which has a rim size of 16 ? 6 1/2JJ, wasformed into a tire wheel assembly (Example) in the following manner. Asteel plate having a thickness of 1.0 mm was worked into an annularshell, a run-flat support member was prepared by fixing elastic ringsdifferent with each other in inner diameter to both legs of the annularshell, and the tire wheel assembly was prepared by inserting the annularshell into a cavity portion of the pneumatic tire. In this Example, apair of humps on the rim were made equal in outer diameter, an innerdiameter of the elastic ring fitted to the rim in a back side of thewheel was made 1.0 mm smaller than an outer diameter of the humps, andan inner diameter of the elastic ring fitted to the rim in a front sideof the wheel was made 0.5 mm larger than the outer diameter of thehumps.

Additionally, for the purpose of comparison, by preparing a run-flatsupport member where inner diameters of a pair of elastic rings weremade equal to the outer diameter of the humps, another tire wheelassembly (Conventional Example) was obtained. This tire wheel assemblyhad a structure which was the same as that of Example except for thatthe thus prepared run-flat support member was used.

For the above two kinds of tire wheel assemblies, working efficiency inrim assembling, and car interior noise during normal traveling, wereassessed in the following measurement methods, and results of theassessment are shown in Table 1.

Working efficiency in rim assembling:

A time required for rim assembling work of each of the tire wheelassemblies were measured. Note that, in the rim assembling work,attention was fully paid to keeping the run-flat support member, whichwas inserted into the cavity portion of the pneumatic tire, from beingdeformed. Results of the assessment are represented in index numberswith a measured value for Conventional Example being set as 100, on thebasis of an inverse of a measured value. A larger value of the indexnumber indicates that the working efficiency in rim assembling isexcellent.

Car interior noise:

Each of the tire wheel assemblies was inflated with an air pressure of220 kPa, and then was installed to a passenger automobile having adisplacement of 2500 cc. Then, a microphone was installed at a positioncorresponding to an ear of a driver on a window side in a driver's seatin a car interior of the automobile, and a sound pressure of carinterior noise thereof was measured when the automobile was run on arough road surface with a speed of 50 km/h. Results of the assessmentare represented in index numbers with a measured value for ConventionalExample being set as 100. A smaller value of the index number indicatesthat the car interior noise is smaller. TABLE 1 Conventional ExampleExample Inner diameters of elastic The same diameter Different diametersrings for left and right ones for left and right ones Rim assembling 100105 workability (index number) Car interior noise (index 100  95 number)

As shown in this Table 1, the tire wheel assembly of Example wasexcellent in working efficiency in rim assembling, and was smaller incar interior noise during normal traveling.

1. A tire wheel assembly where, while a pneumatic tire is fitted to arim of a wheel, inserted into a cavity portion of the pneumatic tire isa run-flat support member being formed of: a pair of elastic ringsfitted to the rim; and an annular shell straddling between the elasticrings, wherein inner diameters of the pair of elastic rings are madedifferent from each other to make an inner diameter of one elastic ringfitted to the rim in a back side of the wheel smaller than an innerdiameter of the other elastic ring fitted to the rim in a front side ofthe wheel.
 2. The tire wheel assembly according to claim 1, wherein theinner diameter of the elastic ring fitted to the rim in the back side ofthe wheel is at least 0.2 mm smaller than the inner diameter of theelastic ring fitted to the rim in the front side of the wheel.
 3. Thetire wheel assembly according to any one of claims 1 and 2, wherein: theinner diameter of the elastic ring fitted to the rim in the back side ofthe wheel is set in a range obtained by adding −1.5 to 0.0 mm to anouter diameter of a hump in the back side of the wheel; and the innerdiameter of the elastic ring fitted to the rim in the front side of thewheel is set in a range obtained by adding −0.2 to 0.7 mm to an outerdiameter of a hump in the front side of the wheel.
 4. The tire wheelassembly according to any one of claims 1 and 2, wherein a reinforcementcore continuous in a circumferential direction of the tire wheelassembly is buried in the elastic ring fitted to the rim in the backside of the wheel.
 5. The tire wheel assembly according to any one ofclaims 1 and 2, wherein a projection continuous in a circumferentialdirection of the tire wheel assembly is provided on one side of aradially inner end portion of the elastic ring fitted to the rim in theback side of the wheel, the one side being outward in an axial directionof the tire wheel assembly.
 6. The tire wheel assembly according toclaim 5, wherein a height and a width of the projection are in ranges of0.4 to 1.5 mm and of 5.0 to 15.0 mm, respectively.
 7. The tire wheelassembly according to any one of claims 1 and 2, wherein a radiallyinner end portion of the elastic ring fitted to the rim in the back sideof the wheel is recessed in the same shape as a hump.